How can I turn a photo into individual mesh objects
Hmm, this is a tricky one. I've done something similar to this but it might be tricky to do without distorting the image. Here are the options that come to mind.

Cutting up the Mesh Manually:

This is probably the most obvious and most tedious option. Import the image as a plane, and meticulously cut apart the mesh using the knife tool, Boolean operators, or whatever else you can think of. Then separate them into individual objects (p in editmode). The texture should remained mapped appropriately. 

Convert to SVG then import

This is what I would probably try first. When you import an SVG file in Blender, it imports the individual colors and segments separately. I know programs exist for converting a standard image to SVG (I can't recommend anything directly sorry) so try to find one and make an SVG version of your image then import that. It will import as a collection of curve objects. 

Objects first

This is a weird one. Make your camera the exact same aspect ratio as your image, then set you image as the camera background. Then, create a mesh and edit the mesh so that you have created separate linked sets of vertices floating behind the positions of the lights on the image. Example mesh consisting of individual sets of vertices, but within the same object: 



Once you have created all of your individual cells, select everything and use the UV map Projection From View option to generate a UV map that maps the image as seen from your camera. Then apply to the image as a texture for your objects using this UV Map. 
Now, separate all the bits by selecting everything in Edit mode, hitting P, and selecting By Loose Parts. You should now have a bunch of individual objects all textured with appropriate bits of your image. 



What are you trying to accomplish ultimately? If you want to create the illusion of a 3D scene you might want to look up some tutorials on camera mapping in Blender. Here is one from BlenderGuru. 

Hope one of these works for you.